1. Field of the Invention
The present invention relates to safety eyewear for use during laser applications, particularly contact lenses for laser safety.
2. Information Disclosure Statement
An important consideration in radiation or laser applications is the safety of the practitioner or user, as well as the safety of those proximate to the radiation source. In medical settings, both a practitioner and support staff must use sufficient precautions to ensure that they do not sustain injuries due to accidental radiation exposure. Of particular concern is the safety of the eyes of those near the laser or radiation source. Errantly directed radiation can cause significant and lasting damage to a person's eye. This damage can take many forms. If a beam used for cutting or vaporizing tissue is directed toward the eye, it could cause damage by cutting the eye. Certain wavelengths are particularly well-absorbed by ocular tissue or blood vessels, and can cause direct or thermal destruction. The damage may be considerable, long-lasting, and could damage vision.
Current state of the art laser eye protection is characterized by mostly bulky laser safety eye glasses that must be worn during laser or radiation applications. For instance, during medical laser treatment procedures, both the doctor(s) carrying out the procedure, support staff, and in many cases the patient must wear these eye protection devices. This constitutes an inconvenience for the doctor and staff in that it may impede vision, for instance when looking through microscopes or when additional vision correction is involved. In the latter case bulky safety glass designs may be required to fit over the vision correction glass.
Alternatives to safety glasses include contact lenses treated to reflect or absorb harmful radiation. This offers the advantage of removing the inconvenience of glasses. If some safety glasses are still desired, for instance to protect the eyes from dust, smoke, or other material, those who require vision correction no longer have to wear large safety glasses over their eyes. Small, light glasses may be used instead.
U.S. Pat. No. 4,848,894 describes a contact lens with laser protection properties. These properties are accomplished by embedding a reflecting or absorbing layer in the lens material, or applying such layer to the convex surface of the lens. The layer may be a Fabry-Perot reflector or a thin film or holographically formed reflective or absorptive interference filter, or an absorbing layer. The disclosure does not include ways to identify the lens as to what wavelengths it protects from, nor does it have any indicators to alert others that the lenses are being worn.
A major disadvantage of contact lenses are that they are very difficult to see, especially after being placed in the eye. It would be difficult for a person to visually confirm whether those near a radiation source are using the safety lenses, unlike conventional safety glasses that are prominent and easy to see when worn. Also, because of their small size and transparency, it may be difficult to distinguish one contact lens for another. This is especially important where lenses are custom made to protect the eye from certain types of radiation, and thus it is important that the correct lens be worn for a specific procedure.
A number of devices and methods have been disclosed for marking contact lenses. Such markings are generally for identifying specific lenses or identifying the front or back surface of the lens, identifying the right or left eye, identifying the proper orientation for toric lenses, and providing prescription information.
U.S. Patent Application No. 2002/0003605 discloses contact lenses with visible marking indicia. The indicia are formed by etching a number of small recessed spots on a surface of the lens to create a visible marking. These markings appear to be primarily intended to allow one to identify specific lenses prior to placement on the eye. There is no indication that such marks would be visible when worn. The markings disclosed would not be easily seen while the lens is located on the eye. The markings are small, colorless, and generally positioned on the periphery of the lens. It would likely be very difficult to see these markings when the lenses are worn, because it is very difficult for the wearer to control rotation of the lens on the eye, and thus the markings may likely be obscured by the eyelids. Additionally, the recesses may also fill with fluid when worn, further decreasing visibility. These factors, in addition to the small size of the markings, make it virtually impossible to ensure that the markings can be visible without close inspection when the lenses are worn.
U.S. Pat. No. 4,616,910 describes a contact lens with a visual indicator to show that the lens is not inside-out. The indicator has the characteristic that it looks different when viewed from the outside surface versus the inside surface of the lens. This marking is intended to be visible to a user prior to being worn. Because of its small size and potential to be hidden behind the eyelids, the indicator would not be visible after the contact is worn.
U.S. Pat. No. 4,194,814 discloses methods for sublimating lens material to create identifying symbols or indicia. A high intensity laser beam is used for creating the indicia by engraving markings on the surface of the lens. These methods produce markings that would not be visible during use, due to either size and location or due to the fact that the engraved areas fill with fluid.
Markings that are made by etching are restricted in that they have to be sufficiently small and at a location on the lens (the periphery) so that the vision of the user is not affected. Also, when the indentations fill with fluid after being put on the eye, this could serve to reduce reflection off the indentations and reduce visibility further. This severely limits the potential of these methods for providing indicia that is easily identifiable while the lens is worn.
U.S. Pat. No. 4,744,647 provides a method for forming a semi-opaque region on a contact lens. The semi-opaque region can be colored, or can form a coded symbol. The method can be used for cosmetic reasons, by forming a semi-opaque region over the iris region, and coloring it to change the apparent color of the iris. It can also be used to form various symbols on the eye, such as to signal left and right eye. Such symbols would probably be small and be on the periphery of the lens. This method would not be desirable for laser safety systems, in that the entire eye must be protected, and forming semi-opaque regions could compromise the ability of the lens surface to protect the eye from harmful radiation.
Patents exist for tinted contact lenses and methods for tinting such lenses, such as U.S. Pat. Nos. 6,164,777 and 6,488,375. These inventions are generally for cosmetic alterations of eye color and are not contemplated as laser safety lenses.
The prior art has not disclosed a contact lens for protection from harmful radiation that additionally features identifying indicia that are highly visible when placed in the eye. Therefore, there exists a need for contact lens specially manufactured to protect a practitioner from radiation during laser or radiation applications, that additionally contains highly visible and easily recognizable indicia to indicate clearly and from a distance that the practitioner is wearing the lenses and that they are the proper protection for a given application.